Dust explosions garnered national attention this week with the catastrophic coal dust explosion at a Wisconsin coal-fired electrical energy plant in conjunction with the reintroduction of the combustible dust bill. While it is undisputed that worker protection is needed concerning combustible particulate solids that generate combustible dust in the manufacturing, non-manufacturing, and grain sectors. A question arises in the protective measures outlined in H.R. 849, “The Worker Protection Against Combustible Dust Explosions and Fires Act,” requiring the U.S. Occupational Safety and Health Administration (OSHA) to issue rules regulating combustible industrial dusts.
Stakeholders throughout the industrial sectors including the public must realize that dust explosions can never be totally prevented unless we completely shut down our manufacturing base and turn into a service based economy. For instance, we can learn from our New Zealand trading partner, where proactive dust explosion control measures are in place in protecting local and export industries.
Since instituting these control measures the amount of dust explosions have been constant as previously occurred without control measures. The only difference is the severity of these incidents have been reduced with measures like explosion venting and deflagration suppression best engineering practices.
Combustible dust explosions follow under the subheading of propagating explosions quite similar to vapor cloud explosions in the refinery and petrochemicals sector where a combustion zone propagates at subsonic speeds wrecking havoc with the damaging effects of overpressure, thermal radiation, and ensuing projectiles. In March 2005, the catastrophic BP Texas City Refinery explosion is an example of a propagating vapor cloud explosion with similar damaging effects like the Imperial Sugar Refinery propagating dust explosion in February 2008.
Developing worker protection legislation in regards to combustible dust explosions as written in the current reintroduced bill fails to take into account many important aspects in providing basic layers of protection for the nation’s workforce. Additionally, solely utilizing the Chemical Safety Boards (CSB) recommendations as a template for the bill without taking into account many other life saving aspects of protection will not fully solve the problem of future incidents.
A good example is the recent catastrophic We Energies coal dust explosion that utilized national consensus National Fire Protection Association (NFPA) combustible dust standards as stipulated in the combustible dust bill, while implementing explosion control measures such as explosion ventilation panels that reduced the severity of the explosion. NFPA combustible dust standards provide excellent guidance in preventing and managing combustible dust fires and explosions but only to a certain level.
Not in Vicinity/In Vicinity Protection
Subsequently, there only so much that can feasibly be done in providing protection concerning life safety, structural integrity, and mission continuity. For instance, the NFPA combustible standard’s primary objectives are to protect occupants not in the immediate vicinity of an explosion and fire. The contractors that suffered burn injuries in the Wisconsin coal dust explosion were in the immediate vicinity and this is where the problem arises in the reintroduced combustible dust bill in not addressing other important issues.
A potential solution in addressing worker protection concerning combustible dust explosions and fires is incorporating key aspects of the OSHA Process Safety Management (PSM) standard. This might be difficult for many to envision since the PSM standard centers around over 130 highly hazardous chemicals (HHC) that are toxic, corrosive, and reactive.
Combustible dust does not fall into any of these categories. But is does fall under one category in the PSM, and that is the explosive effects quite similar to flammable liquids and gases that can cause propagating explosions. Laying aftermath pictures side by side of the BP Texas City incident and Imperial Sugar Refinery explosion would be difficult for many not familiar of the specific processes to differentiate the two. Both caused severe loss of life, injuries, and property damage.
The OSHA PSM does address contractor participation such as ensuring that contractors attend training concerning the hazards of the perspective workplace. Since contractors work in the immediate vicinity of fire and explosion hazards the PSM standard would provide an appropriate basic layer of protection, where the NFPA combustible dust standard does not, with the conflicting objective of occupants not in the immediate vicinity. Why can’t all layers of protection be crafted into the combustible dust bill?
Better yet, instead of another form of costly regulation that creates an administrative overburden requiring a force of over 10,000 OSHA inspectors for implementation, formulate combustible dust workplace protection around the current OSHA Process Safety Management standard (PSM). There is no need to differentiate another propagating explosion as a separate entity when the issue has already been addressed with flammable gases in the current OSHA PSM standard.
In fact many dusts have deadly overpressure effects more damaging than flammable gases. So what’s the difference and why so much of a disconnect? Is loss of life, injuries, and adverse economic damage more important of an issue in the PSM refinery sector than in the manufacturing sector? It’s time the same level of protection be provided for all the nation’s workers.
Layers of Protection
Combining the protection measures of the national consensus NFPA combustible dust standards and the OSHA PSM standard would go a long way in providing appropriate layers of protection. Already the NFPA combustible dust standard outlines process hazard analysis, process safety information, management of change, and many other criteria quite similar to the current PSM standard.
It doesn’t make sense to reinvent the wheel when the protection measures in the current OSHA PSM could provide an excellent guidance in providing workplace protection for the manufacturing and non-manufacturing sectors concerning combustible dust, just like it currently does for the refinery and petrochemical sector. When many stakeholders fail to take into account, is that all the above falls under the same umbrella of propagating explosions.
Fires Now Explosions
To further complicate the confusion of combustible dust hazards is the profusion of misinformation that the media has recently been expounding on concerning over 350 combustible dust explosions since 1980. For instance, after the CSB Combustible Dust Hazard study, submitted to OSHA in 2006 it was 281 combustible dust explosions and fires from the 1980-2005 period.
Then after the June 2008, CBS 60 Minutes segment on combustible dust, the fires from the CSB Dust Hazard Study, all of a sudden evolved into explosions, with the fires not being reported through many media sources. Hence adding to misinformation like a propagating combustion zone where soon the next media outlet, like unreacted dust ahead of the reaction front, will be consumed with more misinformation.
Conflicting Research Data
Most of the combustible dust incidents are fires not explosions. For instance out of the over 150 incidents in 2008 occurring in the manufacturing and non-manufacturing sector only 30 were combustible dust explosions. But don’t get a false sense that this is a mediocre number, since many dust explosions where previously combustible dust related fires, months earlier in prior repeatable incidents.
Incident reporting as stipulated in the OSHA PSM standard would provide stakeholders with a better idea of the probability and severity of occurrences instead of solely relying on incomplete data from governmental and media reports in formulating occupational health and safety policy
There are many more aspects in formulating a solution in developing comprehensive occupational safety measures concerning the hazards of combustible dust in the workplace. Hopefully a few of the above issues will provide insight into the depth and breadth of the issue that at times is like peeling back the many layers of an onion.
The reintroduced combustible dust bill needs to be rewritten to incorporate all layers of safety and not just from the 30,000 foot view following the tragic Imperial Sugar Refinery dust explosion. The future of our nation’s workforce is at stake. Instead of the threat from outside as in Homeland Security regulations, we now have a threat from within. Question is, just how much resources we are all willing to put forward.
Saturday, February 7, 2009
Posted by John Astad at 4:38 PM